1. Windows Azure Anders Hejlsberg Technical Fellow 3-012
7/28/2019
TypeScript
Anders Hejlsberg
Technical Fellow
3-012
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2. Application scale JavaScript development is hard.

3. TypeScript is a language for application scale JavaScript development.

4. TypeScript is a typed superset of JavaScript that compiles to plain JavaScript.

5. TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. Any browser. Any host. Any OS. Open Source.

6. TypeScript Starts with JavaScript
All JavaScript code is TypeScript code, simply copy and paste
All JavaScript libraries work with TypeScript
Optional static types, classes, modules
Enable scalable application development and excellent tooling
Zero cost: Static types completely disappear at run-time
Ends with JavaScript
Compiles to idiomatic JavaScript
Runs in any browser or host, on any OS

7. TypeScript Type System

8. Type System Formalization of JavaScript’s types
Static representation of JavaScript’s dynamic type system
Type inference and structural typing
In practice very few type annotations are necessary
Works with existing JavaScript libraries
Declaration files can be written and maintained separately
Not “provably type safe”
Types reflect intent but do not provide guarantees

9. TypeScript classes and modules

10. Classes and modules Scalable application structuring
Classes, Modules, and Interfaces enable clear contracts between components
Aligned with emerging standards
Class, Module, and Arrow Function syntax aligns with ECMAScript 6 proposals
Supports popular module systems
CommonJS and AMD modules in any ECMAScript 3 compatible environment

11. Application Scale TypeScript

12. TypeScript preview Compiler Tooling Libraries And More
Open Source, written in TypeScript
Tooling
Visual Studio language service, browser hosted playground
Libraries
Static typing of DOM, jQuery, node.js, WinRT, WinJS, …
And More
Lots of samples and formal Language Specification

13. Resources Application scale JavaScript development is hard.
TypeScript makes it easier.
Please submit session evals on the Build Windows 8 App or at